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<div class="section boost_icl_function_reference_segmentational_fineness" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_icl.function_reference.segmentational_fineness"></a><a class="link" href="segmentational_fineness.html" title="Segmentational Fineness">Segmentational
      Fineness</a>
</h3></div></div></div>
<p>
        For overloading tables on infix operators, we need to break down <code class="computeroutput"><a class="link" href="../../boost/icl/interval_set.html" title="Class template interval_set">interval_sets</a></code> and <code class="computeroutput"><a class="link" href="../../boost/icl/interval_map.html" title="Class template interval_map">interval_maps</a></code>
        to the specific class templates
      </p>
<a name="ph_def_S1"></a><a name="ph_def_S2"></a><a name="ph_def_S3"></a><a name="ph_def_M1"></a><a name="ph_def_M3"></a><div class="informaltable"><table class="table">
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              <p>
                <span class="bold"><strong>S1</strong></span>
              </p>
              </td>
<td>
              <p>
                <code class="computeroutput"><a class="link" href="../../boost/icl/interval_set.html" title="Class template interval_set">interval_set</a></code>
              </p>
              </td>
<td>
              <p>
                <span class="bold"><strong>S2</strong></span>
              </p>
              </td>
<td>
              <p>
                <code class="computeroutput"><a class="link" href="../../boost/icl/separate_interval_set.html" title="Class template separate_interval_set">separate_interval_set</a></code>
              </p>
              </td>
<td>
              <p>
                <span class="bold"><strong>S3</strong></span>
              </p>
              </td>
<td>
              <p>
                <code class="computeroutput"><a class="link" href="../../boost/icl/split_interval_set.html" title="Class template split_interval_set">split_interval_set</a></code>
              </p>
              </td>
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              <p>
                <span class="bold"><strong>M1</strong></span>
              </p>
              </td>
<td>
              <p>
                <code class="computeroutput"><a class="link" href="../../boost/icl/interval_map.html" title="Class template interval_map">interval_map</a></code>
              </p>
              </td>
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              <p>
              </p>
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              </p>
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              <p>
                <span class="bold"><strong>M3</strong></span>
              </p>
              </td>
<td>
              <p>
                <code class="computeroutput"><a class="link" href="../../boost/icl/split_interval_map.html" title="Class template split_interval_map">split_interval_map</a></code>
              </p>
              </td>
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<p>
        choosing <span class="bold"><strong>Si</strong></span> and <span class="bold"><strong>Mi</strong></span>
        as placeholders.
      </p>
<p>
        The indices <span class="bold"><strong>i</strong></span> of <span class="bold"><strong>Si</strong></span>
        and <span class="bold"><strong>Mi</strong></span> represent a property called <span class="emphasis"><em><span class="bold"><strong>segmentational fineness</strong></span></em></span> or short <span class="emphasis"><em><span class="bold"><strong>fineness</strong></span></em></span>, which is a <span class="emphasis"><em><span class="bold"><strong>type trait</strong></span></em></span> on interval containers.
      </p>
<div class="informaltable"><table class="table">
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              <p>
                <code class="computeroutput"><span class="identifier">segmentational_fineness</span><span class="special">&lt;</span></code><span class="bold"><strong>Si</strong></span><code class="computeroutput"><span class="special">&gt;::</span><span class="identifier">value</span></code>
                == <span class="bold"><strong>i</strong></span>
              </p>
              </td></tr>
<tr><td>
              <p>
                <code class="computeroutput"><span class="identifier">segmentational_fineness</span><span class="special">&lt;</span></code><span class="bold"><strong>Mi</strong></span><code class="computeroutput"><span class="special">&gt;::</span><span class="identifier">value</span></code>
                == <span class="bold"><strong>i</strong></span>
              </p>
              </td></tr>
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<p>
        Segmentational fineness represents the fact, that for interval containers
        holding the same elements, a splitting interval container may contain more
        segments as a separating container which in turn may contain more segments
        than a joining one. So for an 
</p>
<pre class="programlisting"><span class="keyword">operator</span> <span class="special">&gt;</span>
</pre>
<p>
        where 
</p>
<pre class="programlisting"><span class="identifier">x</span> <span class="special">&gt;</span> <span class="identifier">y</span>   <span class="comment">// means that
</span><span class="identifier">x</span> <span class="identifier">is_finer_than</span> <span class="identifier">y</span>

<span class="comment">// we have
</span>
<span class="identifier">finer</span>                                             <span class="identifier">coarser</span>
<span class="identifier">split_interval_set</span>                           <span class="identifier">interval_set</span>
                   <span class="special">&gt;</span> <span class="identifier">separate_interval_set</span> <span class="special">&gt;</span>  
<span class="identifier">split_interval_map</span>                           <span class="identifier">interval_map</span>
</pre>
<p>
      </p>
<p>
        This relation is needed to resolve the instantiation of infix operators e.g.
        <code class="computeroutput"><span class="identifier">T</span> <span class="keyword">operator</span>
        <span class="special">+</span> <span class="special">(</span><span class="identifier">P</span><span class="special">,</span> <span class="identifier">Q</span><span class="special">)</span></code> for two interval container types <code class="computeroutput"><span class="identifier">P</span></code> and <code class="computeroutput"><span class="identifier">Q</span></code>.
        If both <code class="computeroutput"><span class="identifier">P</span></code> and <code class="computeroutput"><span class="identifier">Q</span></code> are candidates for the result type <code class="computeroutput"><span class="identifier">T</span></code>, one of them must be chosen by the compiler.
        We choose the type that is segmentational finer as result type <code class="computeroutput"><span class="identifier">T</span></code>. This way we do not loose the <span class="emphasis"><em><span class="bold"><strong>segment information</strong></span></em></span> that is stored in the
        <span class="emphasis"><em><span class="bold"><strong>finer</strong></span></em></span> one of the container
        types <code class="computeroutput"><span class="identifier">P</span></code> and <code class="computeroutput"><span class="identifier">Q</span></code>.
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// overload tables for
</span><span class="identifier">T</span> <span class="keyword">operator</span> <span class="special">+</span> <span class="special">(</span><span class="identifier">T</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">P</span><span class="special">&amp;)</span>
<span class="identifier">T</span> <span class="keyword">operator</span> <span class="special">+</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">P</span><span class="special">&amp;,</span> <span class="identifier">T</span><span class="special">)</span>

<span class="identifier">element</span> <span class="identifier">containers</span><span class="special">:</span>     <span class="identifier">interval</span> <span class="identifier">containers</span><span class="special">:</span>
<span class="special">+</span>  <span class="special">|</span> <span class="identifier">e</span> <span class="identifier">b</span> <span class="identifier">s</span> <span class="identifier">m</span>            <span class="special">+</span>  <span class="special">|</span> <span class="identifier">e</span>  <span class="identifier">i</span>  <span class="identifier">b</span>  <span class="identifier">p</span>  <span class="identifier">S1</span> <span class="identifier">S2</span> <span class="identifier">S3</span> <span class="identifier">M1</span> <span class="identifier">M3</span>     
<span class="special">---+--------</span>            <span class="special">---+---------------------------</span>
<span class="identifier">e</span>  <span class="special">|</span>     <span class="identifier">s</span>              <span class="identifier">e</span>  <span class="special">|</span>             <span class="identifier">S1</span> <span class="identifier">S2</span> <span class="identifier">S3</span> 
<span class="identifier">b</span>  <span class="special">|</span>       <span class="identifier">m</span>            <span class="identifier">i</span>  <span class="special">|</span>             <span class="identifier">S1</span> <span class="identifier">S2</span> <span class="identifier">S3</span> 
<span class="identifier">s</span>  <span class="special">|</span> <span class="identifier">s</span>   <span class="identifier">s</span>              <span class="identifier">b</span>  <span class="special">|</span>                      <span class="identifier">M1</span> <span class="identifier">M3</span>  
<span class="identifier">m</span>  <span class="special">|</span>   <span class="identifier">m</span>   <span class="identifier">m</span>            <span class="identifier">p</span>  <span class="special">|</span>                      <span class="identifier">M1</span> <span class="identifier">M3</span>
                        <span class="identifier">S1</span> <span class="special">|</span> <span class="identifier">S1</span> <span class="identifier">S1</span>       <span class="identifier">S1</span> <span class="identifier">S2</span> <span class="identifier">S3</span> 
                        <span class="identifier">S2</span> <span class="special">|</span> <span class="identifier">S2</span> <span class="identifier">S2</span>       <span class="identifier">S2</span> <span class="identifier">S2</span> <span class="identifier">S3</span> 
                        <span class="identifier">S3</span> <span class="special">|</span> <span class="identifier">S3</span> <span class="identifier">S3</span>       <span class="identifier">S3</span> <span class="identifier">S3</span> <span class="identifier">S3</span> 
                        <span class="identifier">M1</span> <span class="special">|</span>       <span class="identifier">M1</span> <span class="identifier">M1</span>          <span class="identifier">M1</span> <span class="identifier">M3</span>
                        <span class="identifier">M3</span> <span class="special">|</span>       <span class="identifier">M3</span> <span class="identifier">M3</span>          <span class="identifier">M3</span> <span class="identifier">M3</span>
</pre>
<p>
      </p>
<p>
        So looking up a type combination for e.g. <code class="computeroutput"><span class="identifier">T</span>
        <span class="keyword">operator</span> <span class="special">+</span>
        <span class="special">(</span><span class="identifier">interval_map</span><span class="special">,</span> <span class="identifier">split_interval_map</span><span class="special">)</span></code> which is equivalent to <code class="computeroutput"><span class="identifier">T</span>
        <span class="keyword">operator</span> <span class="special">+</span>
        <span class="special">(</span><span class="identifier">M1</span><span class="special">,</span> <span class="identifier">M3</span><span class="special">)</span></code>
        we find for row type <code class="computeroutput"><span class="identifier">M1</span></code> and
        column type <code class="computeroutput"><span class="identifier">M3</span></code> that <code class="computeroutput"><span class="identifier">M3</span></code> will be assigned as result type, because
        <code class="computeroutput"><span class="identifier">M3</span></code> is finer than <code class="computeroutput"><span class="identifier">M1</span></code>. So this type combination will result
        in choosing this 
</p>
<pre class="programlisting"><span class="identifier">split_interval_map</span> <span class="keyword">operator</span> <span class="special">+</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">interval_map</span><span class="special">&amp;,</span> <span class="identifier">split_interval_map</span><span class="special">)</span>
</pre>
<p>
        implementation by the compiler.
      </p>
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        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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